At the berlin conference, european powers agreed that, in order to claim part of africa, a european power had to
a. establish missions there to spread the christian faith.
b. set up a government office there.
c. establish businesses there.
d. conquer the ruling african tribes there.

At the Berlin Conference the principle of Effective Occupation was established, that said that a country needed to have an actual presence in the colony to be bale to claim it.

In practice, this meant at least c. establishing businesses there. Additionally, they could make contact and conquer the local rulers. 

I'm not 100 percent sure i say 7 is your answers